Spark plug



May 17, 1921.

. W. G. CLAYTON SPARK PLUG 7 Filed July 12. 1926 Patented May 17, 1927. i i I i UNITE 1;): l

Parent ()FFLQE.

WILLIAM Gnonen c ax'roN, DESI. KILDA, NEAR MELBOURNE, vroronm,

' A E ALI AR I LII Application filed July 12, 1926,5erie1 No. 122,004, and in AustraliaFebruary 26, 1925.

This invention relates to an improved spark plug and has been devised in order to provide a spark plug of greater utility than those at present in use, the essential features embodied in this invention being as fol.low s i I i 1. The arrangement of the electrodes whereby by the operation of the insulation one, two, three or more points may be adjusted to allow of one or more sparks to be operated as required.

2. The insulator is so arranged with positive points that it is interchangeable with any sized plug shell or casing.

3. The use with the features above mentioned of an insulator protruding through the end of the shell with an air space be-' tween the insulator and shell for the purpose of allowing the explosive gases entering high up into the plug so that there is no possibility of the spark or sparks taking place in a vacuum and so ensuring that the spark occurs well into the explosive gases, and also allowing of expansion and contraction of the material forming the casing and insulator.

1. The use of a flexible washer or washers to form joints between the insulation and shell and so that when these parts are screwed down there is no possibility of the cracking or breaking of the insulation.

5. A spark plug comprising a metal shell constituting a negative electrode,and insulator in the negative electrode. a positive electrode extending through said insulator and terminating at a point in proximity to said shell and preferably off-set from the centre of the insulator, a plurality of sparkin g points between the positive electrode and the negative electrode and a portion of said insulator preventing short circuiting between the positive electrode and the nearest portion of the negative electrode and means combining the shell and the insulator whereby the points can be adjusted to allow of a single spark gap or a plurality thereof according to the conditions under which the sparking plug is used, such as a condition necessary to secure a spark of desired intensity.

In order that the invention may be more readily understood it will now be described with reference to the accompanying draw,- ings in which Figure 1 is a side elevatiom the spark gaps can Figure 2 'isa view in plan.

Figure 3 is a view of the underside, and- Figure 4 is a view in section ofthe improved spark plug;

Figure' 5 isa view of the unassembled parts;

According to this invention the preferred construction consists of an insulator 1, the

top portion 2 of which is cylindrical and approximately at its centre is formed with an enlarged circular portion 3 to which a flexible metal washer 4: is fitted and from this portion the insulator tapers as at 5 to the lower end preferably a short distance past the bottom of the shell 6.

Passingthrough this insulator is a positive electrode 7 the top of which is threaded as at Sto receive a nut 9 for the lead wire 10 of the circuit.

This positive electrode 7 projects through the bottom of the insulator 1 and spaced therefrom are one, two or more sparking points 11 with spark gaps 12 separating the same from the positive electrode 7 and being set into the insulator only as illustrated in Figure 4.

The sparking points 11 and the negative electrode 14 are curved towards each other as illustrated in Figure 4 in order to avoid short circuiting at the base of the insulator 1, the points being directed into the gas space to ensure a more positive spark.

The insulator 1 so constructed is received in an outer shell 6 around its'lower portion and this outer shell is threaded at its lower end 13 to be screwed into the cylinder, this lower end being provided with a negative electrode 14 projecting towards the spark gaps 12 in the insulator, an air space 15 being provided between the lower end of the insulator 1 and the shell 6 to perform the functions above described.

In the shell, 6 at the point where the lower end of the insulator 1 tapers downwardly is a conical flexible washer 4t conforming substantially to the shape of that portion of the insulator 1 and which imparts a certain amount of resiliency to prevent the breaking or cracking of the insulator 1 when the parts are locked together by a, locking nut 16 screwing into the casing or shell 6 at the top and around the insulator 1.

By arranging the parts in this way the insulator 1 and shell 6 are interchangeable, be adjusted so that one or more are given according to such adjust lncnt and the lock nut 16 also bears on a flexible metal washer 4.- which allows the combining of the parts together without the fear of breaking the insulator v The insulator can be constructed of'any suitable nonconductive material such as porcelain, mica, lava or any other suitable material and I desireitto be understood that various improvements and modifications may be embodied without departing from the spirit and scope of the invention.

IVhat I claim as my invention and desire to secure by Letters Patent is In a spark plug, a grounded electrode, an insulator, and a plurality of electrodes carried by said insulator the sparking points of which are arranged in chords of arcs of a circle concentric to the axis of said insulator, the circumference of which circle lies Within sparking distance on said grounded electrode, said plurality of electrodes forming a series of spark gaps, and said insulator being adjustable by rotation so as to bring the terminal electrodes of any of said chords into sparking relation With said grounded electrode for the selective production of different numbers of sparks, in series.

Signed at Melbourne, Victoria, Australia, this 1st day of June, 1926.

WILLIAM GEORGE CLAYTON. 

